348 THE LABIATE FAMILY. [ Mentha. 
in the axils of the upper leaves. . Calyx tubular, about 14 lines long, with 
fine pointed teeth. 
In wet ditches, arid marslies, ind on the edges of streams, throughout 
Europe and Russian Asia, and now naturalized in many other countries. 
Abundant in Britain generally, but, like the two following, becomes rarer 
in the north of Scotland. Fl, summer and autumn. [A variety, M. pubes- 
cens, Willd., with narrower sharply serrate leaves and stout cylindric 
spikes, occurs in the midland and southern counties of England. | 
6, M. sativa, Linn. (fig. 783). Whorled Mint.—Intermediate, as it 
were, between JM. aquatica and M. arvensis, this plant has the foliage and 
calyx of the former, but the stem is less erect and often low and spreading, 
as in M. arvensis, and the flowers, as in the latter species, are all in dis- 
tinct axillary whorls, without. any terminal head or spike, or with only a 
very few flowers in the axils of the last pair of floral leaves. Its chief 
_ difference from WM. arvensis is in the more tubular, longer calyx, and larger 
flowers; but intermediate forms are so numerous, connecting it on the one 
hand with M. arvensis, and on the other with M. aquatica, that many 
botanists have considered it as a mere variety of the one or of the other. 
These points cannot be determined without a long course of experiments 
and observations made on a succession of seedlings, which are as rare in 
this as in other species of the genus. 
As widely spread as JM. arvensis, all over temperate and northern 
Europe, and Russian Asia, but growing usually in moister situations and 
richer soils. Common in Britain. Jl. summer and autumn. [This in- 
cludes many distinct British varieties, distinguished as species by some 
botanists, as M, rubra, Sm., with the nerves of the leaf purple; J. gra- 
cilis, Sm., a very slender form with narrow floral leaves; VM. pratensis, 
Sole., with drooping leaves rounded at both ends; and J. gentilis, Linn., 
with large floral leaves, the uppermost flowerless. | 
7. WE. arvensis, Linn. (fig. 784). Corn Mint.—Usually a low, spread- 
ing, branched perennial, more or less hairy, with a creeping rootstock, and 
annual stems, from 6 inches to a foot long, rarely rising erect to the 
height of 1 or 2 feet. Leaves stalked, ovate, and toothed, 1 to 2 inches 
long, or the upper ones smaller. Flowers all in axillary whorls, mostly 
shorter than the leafstalks ; the last pair of leaves without any or with 
only very few flowers, Calyx campanulate, seldom above a line long, with 
short teeth. Corolla twice as long. 
In fields and moist places, in temperate and northern Europe and Rus- 
sian Asia; rarer to the southward, but introduced with cultivation into 
many other parts of the globe. Abundant in Britain, although less so 
than M. aquatica, and, like that species, becomes rarer towards the north 
of Scotland. Fl. summer and autumn. It varies much in stature, in. 
hairiness, in the size of the leaves, etc. 
8, M. Pulegium, Linn. (fig. 785). Pennyroyal Mint, Pennyroyal. 
—A prostrate, much branched perennial, with the leaves very much smaller 
than in any other Mentha, being seldom above half an inch long, and quite 
entire or seldom slightly crenate; the floral ones still smaller, and often 
recurved. Flowers in dense axillary whorls, like those of M. arvensis, 
except that the calyx-teeth are less regular, with the mouth closed by hairs, 
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